The problem of physically connecting one part, such as a pipe, to another has historically been resolved (across all engineering disciplines) by means of a screw-threaded engagement. This requires one part to include a helical projection (i.e. thread) and the other to include a complementary recess such that relative rotation or screwing of one part with respect to the other permits engagement therebetween. While such a connecting mechanism is adequate in many circumstances, the act of screwing one part onto the other can be time-consuming and can require significant physical exertion for an operator, particularly when large and/or heavy parts are involved.
The considerations described above are particularly apparent in the oil and gas exploration and extraction industry where many large and heavy parts are often required to be connected. For example, a drill pipe string of several miles long may be manually constructed on a rig by screwing many individual tubular metal sections, in the form of pipe sections or stands, together. In certain operations, a relatively large diameter riser will be provided between the wellhead and the drill rig. The riser is also made up of several individual tubular metal sections which are commonly made up by screwing together on the rig. More recently, an improved coupling has been employed, as described in WO2009/101279, in which portions of a riser are provided with a male and a female connector element, the male connector element having a locking ring mounted thereon which has a series of lugs configured for engagement with a complementary series of lugs on the female connector element. While this arrangement takes less time and is less strenuous to operate than a traditional screw-threaded connection, the configuration requires manual connection of a further element in the form of an auxiliary tube attached to the side of the riser, so as to provide the required level of strength, security and functionality.
In other operations in this industry, tools, valves, packers, sensors and other devices are lowered into and retrieved from well bores using flexible relatively small diameter supports constituted, for example, by coil tubing, slickline or wireline. The support passes through a lubricator stuffing box and grease head comprising a tubular body mounted above an opening providing access into the well bore. The lubricator may be supported in a derrick or from a crane jib. The lubricator provides a lock via which tools may be inserted into and retrieved from a well which is under pressure. To insert a tool, the well is closed below the lubricator and pressure within the lubricator is bled off. The lubricator is then opened to receive the tool, which is coupled to the end of the support. The lubricator is then closed and the well opened below the lubricator, allowing the tool to be run into the well.
Typically, a lubricator will be assembled along with other items of temporary surface pressure control equipment into a so-called rig-up. The precise structure of the rig-up will vary depending on the nature of the work being performed. At present, each piece of equipment forming the rig-up is fitted together manually using standard screw-threaded Bowen and Otis type quick union couplings. These couplings generally comprise a male component, a female component and a heavy collar which is rotatably mounted on the male component and includes a screw-thread for engagement with a complementary thread provided on the female component. An O-ring seal is provided between the male and female components to contain the well pressure and/or fluid. However, such couplings are difficult and time-consuming for an operator to assemble and disassemble. For example, a conventional Otis lubricator has an 11.5 inch (29.2 cm) diameter thread which requires approximately 16 turns of the collar to fully engage the male and female components. It is also common for debris and well fluid to make thread engagement difficult. In addition, working with conventional couplings involves heavy manual handling.
Furthermore, the rig-up is usually partially assembled directly onto the well head and partially assembled in the horizontal position on a rig deck, this latter section then being raised into a vertical position before being connected to the well head assembly. During operations with the rig-up in a vertical position, the connection above the wireline valve has to be repeatedly broken to change tools. This is done by an operator working at height—often suspended in a harness. It will be appreciated that the traditional couplings described above will be even more difficult and time-consuming to assemble and disassemble when working in such conditions.
It is therefore an aim of the present invention to provide a connector that addresses at least some of the afore-mentioned problems.